Live to Die Another Day: Regeneration in Diopatra aciculata Knox and Cameron, 1971 (Annelida: Onuphidae) Collected as Bait in Knysna Estuary, South Africa

Abstract

Regeneration is critical for survivorship after injury, sublethal predation, and asexual reproduction; it allows individuals to recover, potentially enabling populations of bait species to overcome the effects of bait collection through incidental asexual reproduction. Opportunities for regeneration are created when worms break during collection (which happens more often than not) and are thrown back into the estuary. Additionally, the trade and movement of bait could result in the range expansion of invasive species. This study investigated bait collection habits of local fishermen and the in situ incidence of regeneration in the estuarine moonshine worm, Diopatra aciculata. The evidence shows that this species is capable of anterior and posterior regeneration. The disproportionately small percentage of worms that seem to be recovering from the degree of damage that may be inflicted during bait collection suggests that regeneration may not help worms to withstand the effects of bait collection. However, the continuous movement and discarding of even small numbers of bait in other estuaries can lead to range expansion through incremental build-up, forming new populations, if these fragments are large enough to regenerate.

An Introduction to Diopatra, the Amazing Ecosystem Engineering Polychaete

“…The genus Diopatra is known as an important ecosystem engineer in sedimentary systems, creating refugia and stabilizing sediments when in sufficient density [3,7,64,74,75]. It is also an important prey item for a variety of predators and used worldwide as bait [44,[70][71][72]78,84]. However, our knowledge of the genus is quite limited as was revealed recently when the large and common onuphid of the Atlantic coast of Europe was found to be a protandric sequential hermaphrodite [12].…”

“…Interestingly, D. aciculata is also harvested as a bait species in South Africa, occurring in the Knysna Estuary, where it has been known as the moonshine worm for the last three decades [83]. A review of the Knysna Estuary bait industry is presented in this SI (see paper by Schoeman and Simon, 2023) [84].…”

“…[89] studied whether D. neapolitana (Figure 6B) can regenerate body damage caused by bait digging or predation and subsequently found that the species' regenerative capacity proved to be affected by abiotic factors, such as seawater pH, temperature, or salinity, and thus can be used as sensitive markers to assess the metabolic effects of current climate change on marine invertebrate species [90]. In connection with studying bait collection in the Knysna Estuary, South Africa, the in situ incidence of regeneration in D. aciculata was investigated [84]. Although the species has a great capacity for regeneration, the small percentage of recovering worms does not negate the effects of bait collection (see paper by Schoeman and Simon, 2023 [84] in this SI).…”

“…In connection with studying bait collection in the Knysna Estuary, South Africa, the in situ incidence of regeneration in D. aciculata was investigated [84]. Although the species has a great capacity for regeneration, the small percentage of recovering worms does not negate the effects of bait collection (see paper by Schoeman and Simon, 2023 [84] in this SI).…”

Investigating the developmental onset of regenerative potential in the annelid Capitella teleta

“…Although we cannot currently identify trends reflecting how regeneration abilities change between larval and adult stages from a phylogenetic perspective, we can consider the impact of life history factors. Factors such as feeding (de Jong & Seaver, 2016;Zattara & Bely, 2013), duration of larval stage, and sublethal predation (Schoeman & Simon, 2023;Stewart, 1998) may better correlate with the regenerative abilities observed in an individual species. Unlike larvae of C. teleta, larvae of M. alaskensis, P. flava, and P. miniata feed and display an ability to replace complex structures following amputation.…”